See that little blue arc at about 8 o'clock? I have read somewhere that this little arc just possibly shows us where the companion of Tycho's supernova is located.

Like the caption said, astronomers have suspected that the companion survived the explosion. Tycho's supernova was a supernova type Ia, where a white dwarf accretes matter from a nearby companion, until the white dwarf gets "overloaded" and breaks through the Chandrasekhar limit, causing a runaway deflagration of the white dwarf star which explodes with a predicted luminosity. The predictability of the luminosity of supernovas type Ia makes these exploding white dwarfs particularly useful as standard candles at cosmological distances.

Wouldn't it be fun if the companion of the white dwarf that became Tycho's supernova could be found? And wouldn't it be fun if the little "blue" (really X-ray) arc could point us to where it is located?

Tycho G has been proposed as the surviving binary companion star of the SN 1572 supernova event. The star is located about 12,000 light-years away in the constellation Cassiopeia. It is a subgiant, similar to our Sun in temperature, but more evolved and luminous.
...
Tycho G is travelling away from us at nearly 80 km/s, much faster than the mean velocity of other stars in its stellar neighbourhood. It matches the properties of some models for the pre-supernova star system, although other studies exclude it.

If the star is a subgiant, it might just possibly have been a true giant before it was robbed of much of its mass by a "vampire-like", gas-sucking white dwarf companion.

Alastair asks for help to scale this, and so do I!
surfing around the subject, the Remnant is said to tbe 8-9000 light years away, and G 12000! Some companion star!
And how big is the remnant now. There is a NASA video that purports to show changes in the cloud as it continues to expand - https://www.youtube.com/watch?v=cPG27uaJC3U, so it must be moving pretty fast, and so after 400 years could it be several hundred LY across?

Ann is the colour queen, but these are X-ray frequencies. There's a video in the Wiki page linked to from the blurb (Tycho's supernova remnant) that breaks down the three frequencies used.
John

Don't understand how that can be, Ann.
The way the luminosity fades will be the same however far away it is.
But as a "standard candle", an SN that appears to have brightness of 1, while one that is twice as far away will have a brightness of 1/SQR(2)?

Don't understand how that can be, Ann.
The way the luminosity fades will be the same however far away it is.
But as a "standard candle", an SN that appears to have brightness of 1, while one that is twice as far away will have a brightness of 1/SQR(2)?

John

Well, the way I understand it, we are dependent on Tycho's observations in 1572 and 1573 to estimate the distance to the supernova. I guess that, as reliable as Tycho was for his time, his observations still weren't as good as modern observations. That's where the uncertainties come from.

But Gaia should hopefully settle this uncertainty once and for all. If nothing else, Gaia should defintely be able to pin down the distance to the supernova's possible companion, Tycho G.

<<Tycho's supernova was classified as type I on the basis of its historical light curve soon after type I and type II supernovae were first defined on the basis of their spectra. The X-ray spectrum of the remnant showed that it was almost certainly of type Ia, but its exact classification continued to be debated until the detection of a light echo in 2008 gave final confirmation that it is a normal type Ia.

The classification as a type Ia supernova of normal luminosity allows an accurate measure of the distance to SN 1572. The peak absolute magnitude can be calculated from the B-band decline rate to be −19.0±0.3.Given estimates of the peak apparent magnitude and the known extinction of 1.86±0.2 magnitudes, the distance is 3.8+1.5−0.9 kpc.

The distance to the supernova remnant has been estimated to between 2 and 5 kpc (approx. 6,500 and 16,300 light-years), but recent studies suggest a value closer to 2.5 and 3 kpc (approx. 8,000 and 9,800 light-years).>>

<<This image from NASA's Wide-field Infrared Survey Explorer (WISE) takes in several interesting objects in the constellation Cassiopeia, none of which are easily seen in visible light. The red circle visible in the upper left part of the image is SN 1572, often called "Tycho's Supernova." This remnant of a star explosion is named after the astronomer Tycho Brahe, although he was not the only person to observe and record the supernova. When the supernova first appeared in November 1572, it was as bright as Venus and could be seen in the daytime. Over the next two years, the supernova dimmed until it could no longer be seen with the naked eye. It wasn't until the 1950s that the remnants of the supernova could be seen again with the help of telescopes.

When the star exploded, it sent out a blast wave into the surrounding material, scooping up interstellar dust and gas as it went, like a snow plow. An expanding shock wave traveled into the surroundings and a reverse shock was driven back in toward the remnants of the star. Previous observations by NASA's Spitzer Space Telescope indicate that the nature of the light that WISE sees from the supernova remnant is emission from dust heated by the shock wave.

In the center of the image is a star-forming nebula of dust and gas, called S175. This cloud of material is about 3,500 light-years away and 35 light-years across. It is being heated by radiation from young, hot stars within it, and the dust within the cloud radiates infrared light. On the left edge of the image, between the Tycho supernova remnant and the very bright star, is an open cluster of stars, King 1, first catalogued by Ivan King, an astronomer at UC Berkeley, Calif. This cluster is about 6,000 light-years away, 4 light-years across and is about 2 billion years old.

Also of interest in the lower right of the image is a cluster of infrared-emitting objects. Almost all of these sources have no counterparts in visible-light images, and only some have been catalogued by previous infrared surveys. There are indications that they may be young stellar objects associated with a dense nebula in the area. Young stellar objects (YSOs) are stars in their earliest stages of life. YSOs are surrounded by an envelope of dust, which would explain the very red color of the sources in this image.

All four infrared detectors aboard WISE were used to make this mosaic. The image spans an area of 1.6 x 1.6 degrees on the sky or about 3 times as wide and high as the full moon. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is dominated by light from stars. Green and red represent light at 12 and 22 microns, which is mostly light from warm dust.>>

https://en.wikipedia.org/wiki/SN_1572#In_literature wrote:
<<In the ninth episode of James Joyce's Ulysses, Stephen Dedalus associates the appearance of the supernova with the youthful William Shakespeare, and in the November 1998 issue of Sky & Telescope, three researchers from Southwest Texas State University, Don Olson and Russell Doescher of the Physics Department and Marilynn Olson of the English Department, argued that this supernova is described in Shakespeare's Hamlet, specifically by Bernardo in Act I, Scene i.>>

STEPHEN: (Stringendo) He has hidden his own name, a fair name, William,

in the plays, a super here, a clown there, as a painter of old Italy
set his face in a dark corner of his canvas. He has revealed it in the
sonnets where there is Wil{L IN OVER}plus. Like John o’Gaunt his name
is dear to him, as dear as the coat and crest he toadied for, on a bend
sable a spear or steeled argent, honorificabilitudinitatibus, dearer
than his glory of greatest shakescene in the country. What’s in a
name? That is what we ask ourselves in childhood when we write the name
that we are told is ours. A star, a daystar, a firedrake, rose at his
birth. It shone by day in the heavens alone, brighter than Venus in the
night, and by night it shone over delta in Cassiopeia, the recumbent
constellation which is the signature of his initial among the stars.
His eyes watched it, lowlying on the horizon, eastward of the bear,
as he walked by the slumberous summer fields at midnight returning
from Shottery and from her arms.

—What is that, Mr Dedalus? the quaker librarian asked. Was it a
celestial phenomenon?

—A star by night, Stephen said. A pillar of the cloud by day.-----------------------------------------------------------------
THE Tragicall Historie of HAMLET Prince of Denmarke

By William Shake-speare (Quarto 1, 1603).

First Scene:

As it hath beene diuerse times acted by his Highnesse ser-
uants in the Cittie of London: as also in the two V-
niuersities of Cambridge and Oxford, and else-where
At London printed for N.L. and Iohn Trundell. 1603.

Barnardo: Sit downe I pray, and let vs once againe

Assaile your eares that are so fortified,
What we haue two nights seene.

Horatio: Wel, sit we downe, and let vs heare Bernardo speake of this.

Barnardo: Last night of al, when yonder starre that's west-

ward from the pole, had made his course to
Illumine that part of heauen. Where now it burnes,
The bell then towling one.

-----------------------------------------------------------------

Last Scene:

Enter Fortenbrasse, Drumme and Souldiers.

Fortenbrasse: Captaine, from vs goe greete The king of Denmarke:

Tell him that For[T]enbrasse nephew to old Norwa[Y],
Craues a free passe and condu[Y]t ouer his land,
According to t[H]e Articles agreed on:
You know [O]ur Randevous, goe march away.